1. Field of the invention
The present invention relates to an apparatus for removing an image forming substance, such as toner, from a recording medium, such as paper, on which the image forming substance is deposited for thereby recycling the recording medium, and more particularly to an apparatus for effectively removing the image forming substance from both sides of the recording medium.
2. Discussion of the Background Art
With the recent spread of printers and copying machines employing various kinds of image forming processes such as an electrophotographic method, a thermal transfer method or an ink-jet method using a hot-melt ink, a large quantity of paper sheets are being used and consumed. This has caused the problems of environmental disruption of the earth due to deforestation because the paper generally used as the recording medium contains pulp as a raw material. In addition, with the increase of consumption of such paper, the problem of waste treatment has become serious.
A transparent sheet is also used as the recording medium for an overhead projector (OHP). Such a transparent sheet employs as a base material a plastic film such as a polyester film. Most of the raw materials for use in such a plastic film are made of petroleum. It is therefore desirable to make efficient use of resources of such a recording medium with the drain of oil resources taken into consideration. In addition, most plastic films have no biodegradability, so that after these plastic films are discarded, they will float on the ocean as dust. It follows as a consequence that environmental disruptions are induced by the use of a recording medium for an overhead projector.
In order to solve the above problems, used paper or film sheets may be collected and subjected to beating or melting again to recycle such recording mediums. However, energy is not efficiently used in such a recycling method, with the result that the cost of the recycled sheets may be higher as compared with the case where paper and film sheets are made of new raw materials, or the quality of the papers and films obtained by the above-mentioned recycling method is lowered.
Recently there have been proposed a few methods and apparatuses for recycling paper and film sheets on which images are deposited by the electrophotographic process. As one of these methods, as disclosed in Japanese Laid-Open Patent Application (KOKAI) 7-84396, there is proposed a method which includes the steps of impregnating a recording medium having an image forming substance, such as a toner image, deposited thereon with an image removal promoting liquid to weaken the adhesion between the recording medium and the image forming substance deposited on the recording medium by the electrophotographic process; pressurizing or heating the recording medium containing the image forming substance to melt or soften the image forming substance; contacting the image forming substance with an image separating material which is constructed of a substance for making the image forming substance tend to be more easily attached onto the surface of the image separating material in comparison with the recording medium including the liquid, i.e., the image separating material adheres to the image forming substance greater than the image forming substance adheres to the recording medium after treatment by the liquid; and peeling the image forming substance from the recording medium by transferring the image forming substance onto the image separating material. This recycling method has the advantages that images formed on a plain copy paper sheet for general use can also be removed therefrom, and there is no problem in terms of safety and hygiene.
In this reference there is proposed an apparatus having a pair of image separating materials for removing image forming substances deposited on both sides of an image recording medium.
However, in a case the image separating material is incompletely cleaned in this apparatus, there are problems that the pair of the image separating materials cling to each other by the melted or softened image forming substance between them, as the image forming substance becomes sticky when it melts or softens and the image separating material is constructed of a substance for making the image forming substance tend to be more easily attached onto the surface of itself in comparison with the recording medium after treatment by the liquid. In a case of using the pair of the image separating materials, there are the same problems if not using the image removal promoting liquid.
There is proposed another apparatus for recycling both-sided copying paper by the same applicant of the present invention as disclosed in Japanese Laid-Open Patent Application (KOKAI) 7-175381. This apparatus includes a recycling unit that uses the method as disclosed in the Japanese Laid-Open Patent Application (KOKAI) 7-84396 and a reversal unit for putting back the image recording material with the removed image forming substance on one side to the recycling unit through a feedback route. However, in this apparatus there are drawbacks of complicating a structure of the apparatus.